1. Field of the Invention
The present invention relates to a lens assembly in which a lens is inserted into a lens frame, and an imaging device having the lens assembly.
2. Description of Related Art
Recently, cameras for watching places of the dead angle for drivers have been equipped with motor vehicles. Further, in department stores or mansions, many fixed-point cameras for monitoring have been arranged.
Since these cameras are frequently provided outside, such a strict waterproof performance or a dustproof function as to withstand an outdoor environment are required. Accordingly, a certain lens assembly applied to such a camera has a structure that space rings for determining spaces between a plurality of lenses are inserted in order into a hollow part of a lens frame and an opening located in an object side is finally sealed by the lens located at a part nearest to the object side so that the water proof performance or the dustproof performance can be obtained.
However, in such a structure, when the lenses are bonded and fixed, since adhesive agent applying parts as described in JP-A-2001-027723 need to be provided in the lens frame, a mechanism of the lens frame is complicated and enlarged. Further, in the structure disclosed in JP-A-2001-027723, since adhesive layers for bonding the lenses to the lens frame are not seen from a front surface, whether or not an adhesive agent effectively infiltrates into the adhesive layers cannot be recognized. If the adhesive agent does not infiltrate into the adhesive layers, when the lens assembly is used to be mounted on a vehicle, there is a fear that the lenses may move due to the vibration of the motor vehicle or the optical axes of the lenses adjusted during an assembly may be shifted so that an initial performance is not satisfied.